Refrigerant detection and control of hvac system

ABSTRACT

A heating, ventilation, and/or air conditioning (HVAC) system includes a heat exchanger configured to exchange heat between a refrigerant and an air flow, a blower configured to induce the air flow across the heat exchanger, and a control board configured to receive an input indicative of a presence of refrigerant external to the heat exchanger and adjust operation of the blower based on the input.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S.Provisional Application Ser. No. 62/988,761, entitled “REFRIGERANTDETECTION AND CONTROL OF HVAC SYSTEM,” filed Mar. 12, 2020, which ishereby incorporated by reference in its entirety for all purposes.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present techniques,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

A heating, ventilation, and/or air conditioning (HVAC) system may beused to thermally regulate an environment, such as a building, home, orother structure. The HVAC system may utilize a refrigerant thatexchanges heat with a fluid, such as air or water, to cool or heat thefluid. The air may be supplied to the environment in order to conditionthe environment, or the water may be used heat or cool air or otherfluids. The refrigerant may exchange heat with the fluid while disposedwithin a heat exchanger of the HVAC system. In some instances, duringoperation of the HVAC system, refrigerant may escape the HVAC system,such as at the heat exchanger or other component of the HVAC system.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

In one embodiment, a heating, ventilation, and/or air conditioning(HVAC) system includes a heat exchanger configured to exchange heatbetween a refrigerant and an air flow, a blower configured to induce theair flow across the heat exchanger, and a control board configured toreceive an input indicative of a presence of refrigerant external to theheat exchanger and adjust operation of the blower based on the input.

In another embodiment, a non-transitory computer-readable storage mediumfor a heating, ventilation, and/or air conditioning (HVAC) systemincludes instructions that, when executed by a processor, cause theprocessor to receive an input indicative of a presence of refrigerantexternal to a heat exchanger of the HVAC system and adjust operation ofa blower of the HVAC system based on the input.

In yet another embodiment, a heating, ventilation, and/or airconditioning (HVAC) system includes a heat exchanger configured toexchange heat between a refrigerant and an air flow, a blower configuredto induce the air flow across the heat exchanger, and a control board.The control board includes a thermostat relay configured to selectivelysupply and suspend power to a thermostat of the HVAC system, a blowerrelay configured to selectively supply and suspend power to the blower,and a processor configured to control the thermostat relay and theblower relay. The processor is configured to receive an input indicativeof a presence of the refrigerant external to the heat exchanger andadjust operation of the blower via the blower relay based on the input.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the present disclosure may be better understood uponreading the following detailed description and upon reference to thedrawings, in which:

FIG. 1 is a perspective view of an embodiment of a heating, ventilation,and/or air conditioning (HVAC) system for building environmentalmanagement that may employ one or more HVAC units, in accordance with anaspect of the present disclosure;

FIG. 2 is a perspective view of an embodiment of a packaged HVAC unit,in accordance with an aspect of the present disclosure;

FIG. 3 is a perspective view of an embodiment of a residential, splitHVAC system, in accordance with an aspect of the present disclosure;

FIG. 4 is a schematic of an embodiment of a vapor compression systemthat may be used in an HVAC system, in accordance with an aspect of thepresent disclosure;

FIG. 5 is a schematic of an embodiment of an HVAC system having arefrigerant detection and control system, in accordance with an aspectof the present disclosure;

FIG. 6 is a schematic of an embodiment of an HVAC system having arefrigerant detection and control system, in accordance with an aspectof the present disclosure; and

FIG. 7 is a schematic of an embodiment of an HVAC system having arefrigerant detection and control system, in accordance with an aspectof the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will bedescribed below. These described embodiments are only examples of thepresently disclosed techniques. Additionally, in an effort to provide aconcise description of these embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but may nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

Generally, a heating, ventilation, and/or air conditioning (HVAC) systemmay be used to thermally regulate an environment, such as a building,home, or other structure. For example, a circuit of the HVAC system maycirculate a refrigerant that exchanges heat with an air flow to beprovided to the environment, thereby cooling or heating the air flow.For example, a heat exchanger disposed along the circuit may route therefrigerant therethrough, and the air flow may be directed over oracross the heat exchanger to facilitate heat exchange between therefrigerant and the air flow. In some instances, refrigerant may escapethe HVAC system, such as at or proximate to the heat exchanger. Forexample, refrigerant may escape from a coupling between components ofthe heat exchanger, from tubing of the heat exchanger, from otherportion(s) of the heat exchanger, and/or from other components of theHVAC system coupled to the heat exchanger. The escaped refrigerant maymix with the air flow and/or other fluids circulating through the HVACsystem.

Accordingly, the present disclosure provides systems and methodsconfigured to detect refrigerant escaped from the circuit of the HVACsystem, such as refrigerant that is external to the heat exchanger ofthe HVAC system, and to control the HVAC system based on the detection.For example, the HVAC system may include a controller that receives anindication (e.g., a signal) that refrigerant is present outside of theheat exchanger. The signal may be received from a sensor of the HVACsystem, such as a sensor disposed at or proximate to the heat exchangerthat is configured to detect a presence of refrigerant. The controllermay include a control board that controls operation of the HVAC systemin response to the detected presence of refrigerant outside the heatexchanger. For example, in response to determining that refrigerant ispresent external to the heat exchanger, the control board may removepower from a thermostat of the HVAC system that enables and controlsgeneral (e.g., normal) operation of the HVAC system. As used herein,general operation of the HVAC system may include operation of heatexchanger(s), a compressor, expansion valve(s), and/or other componentsof the HVAC system to provide conditioning, operation in one or morestandard operating modes (e.g., a heating mode, a cooling mode, a reheatmode, a dehumidification mode), operation based on a parameter (e.g.,temperature, humidity) set point, and/or other suitable operations ofthe HVAC system. Additionally, in response to determining thatrefrigerant is detected external to the heat exchanger, the controlboard may supply power to a blower of the HVAC system that induces anair flow through or along the HVAC system, such as across the heatexchanger, thereby dispersing refrigerant that is located external tothe heat exchanger.

In certain embodiments, in response to determining that refrigerant ispresent external to the heat exchanger, the control board may removepower from one or more other components (e.g., one or more componentsother than the thermostat) that enable general operation of the HVACsystem. For example, the control board may remove power from anothercontrol system (e.g., a control system different from the thermostat)configured to enable and control general operation of the HVAC system.Additionally or alternatively, the control board may remove power fromone or more other components of the HVAC system, such as a compressor, aheat exchanger, an expansion valve, and/or other suitable components. Insuch embodiments, the thermostat may be battery-powered, but operationand control of the HVAC system via the thermostat may be suspended(e.g., disabled) based on the control board removing power from the oneor more other components of the HVAC system.

As discussed in detail below, controlling operation of the HVAC systembased on the determination that refrigerant is present external to theheat exchanger enables the HVAC system to reduce or prevent additionalrefrigerant from escaping the heat exchanger, reduce an amount and/or aconcentration of the refrigerant mixed with air adjacent to and/orflowing across the heat exchanger, and comply with certain industrystandards. For example, suspending general operation of the HVAC systemmay reduce and/or prevent refrigerant from escaping the HVAC system.Further, inducing an air flow through the HVAC system (e.g., across theheat exchanger), via the blower, may facilitate dispersion ofrefrigerant in the air flow supplied to the conditioned environmentand/or may direct refrigerant to another location separate from theconditioned environment, such as an enclosed cabinet of the HVAC system,an area outside a structure having the conditioned environment, or othersuitable areas. Additionally, based on industry standards, it may bedesirable to achieve reduced amounts or concentrations of refrigerantlocated external to the HVAC system and/or to adjust operation of theHVAC system within a specific period of time upon detection ofrefrigerant external to HVAC system components. As such, the systems andmethods described herein improve/facilitate operation, maintenance, andmanagement of the HVAC system.

Turning now to the drawings, FIG. 1 illustrates an embodiment of aheating, ventilation, and/or air conditioning (HVAC) system forenvironmental management that may employ one or more HVAC units. As usedherein, an HVAC system includes any number of components configured toenable regulation of parameters related to climate characteristics, suchas temperature, humidity, air flow, pressure, air quality, and so forth.For example, an “HVAC system” as used herein is defined asconventionally understood and as further described herein. Components orparts of an “HVAC system” may include, but are not limited to, all, someof, or individual parts such as a heat exchanger, a heater, an air flowcontrol device, such as a fan, a sensor configured to detect a climatecharacteristic or operating parameter, a filter, a control deviceconfigured to regulate operation of an HVAC system component, acomponent configured to enable regulation of climate characteristics, ora combination thereof. An “HVAC system” is a system configured toprovide such functions as heating, cooling, ventilation,dehumidification, pressurization, refrigeration, filtration, or anycombination thereof. The embodiments described herein may be utilized ina variety of applications to control climate characteristics, such asresidential, commercial, industrial, transportation, or otherapplications where climate control is desired.

In the illustrated embodiment, a building 10 is air conditioned by asystem that includes an HVAC unit 12. The building 10 may be acommercial structure or a residential structure. As shown, the HVAC unit12 is disposed on the roof of the building 10; however, the HVAC unit 12may be located in other equipment rooms or areas adjacent the building10. The HVAC unit 12 may be a single package unit containing otherequipment, such as a blower, integrated air handler, and/or auxiliaryheating unit. In other embodiments, the HVAC unit 12 may be part of asplit HVAC system, such as the system shown in FIG. 3, which includes anoutdoor HVAC unit 58 and an indoor HVAC unit 56.

In any case, the HVAC unit 12 may be an air cooled device thatimplements a refrigeration cycle to provide conditioned air to thebuilding 10. For example, the HVAC unit 12 may include one or more heatexchangers across which an air flow is passed to condition the air flowbefore the air flow is supplied to the building. In the illustratedembodiment, the HVAC unit 12 is a rooftop unit (RTU) that conditions asupply air stream, such as environmental air and/or a return air flowfrom the building 10. After the air is conditioned, the HVAC unit 12 maysupply the conditioned air to the building 10 via ductwork 14 extendingthroughout the building 10 from the HVAC unit 12. For example, theductwork 14 may extend to various individual floors or other sections ofthe building 10. In some embodiments, the HVAC unit 12 may include aheat pump that provides both heating and cooling to the building 10, forexample, with one refrigeration circuit implemented to operate inmultiple different modes. In other embodiments, the HVAC unit 12 mayinclude one or more refrigeration circuits for cooling an air stream anda furnace for heating the air stream.

A control device 16, one type of which may be a thermostat, may be usedto designate the temperature of the conditioned air. The control device16 also may be used to control the flow of air through the ductwork 14.For example, the control device 16 may be used to regulate operation ofone or more components of the HVAC unit 12 or other equipment, such asdampers and fans, within the building 10 that may control flow of airthrough and/or from the ductwork 14. In some embodiments, other devicesmay be included in the system, such as pressure and/or temperaturetransducers or switches that sense the temperatures and pressures of thesupply air, return air, and/or the like. Moreover, the control device 16may include computer systems that are integrated with or separate fromother building control or monitoring systems, and even systems that areremote from the building 10. In some embodiments, the HVAC unit 12 mayoperate in multiple zones of the building and may be coupled to multiplecontrol devices that each control flow of air in a respective zone. Forexample, a first control device 16 may control the flow of air in afirst zone 17 of the building, a second control device 18 may controlthe flow of air in a second zone 19 of the building, and a third controldevice 20 may control the flow of air in a third zone 21 of thebuilding.

FIG. 2 is a perspective view of an embodiment of the HVAC unit 12. Inthe illustrated embodiment, the HVAC unit 12 is a single package unitthat may include one or more independent refrigeration circuits andcomponents that are tested, charged, wired, piped, and ready forinstallation. The HVAC unit 12 may provide a variety of heating and/orcooling functions, such as cooling only, heating only, cooling withelectric heat, cooling with dehumidification, cooling with gas heat, orcooling with a heat pump. As described above, the HVAC unit 12 maydirectly cool and/or heat an air stream provided to the building 10 tocondition a space in the building 10.

As shown in the illustrated embodiment of FIG. 2, a cabinet 24 orenclosure encloses the HVAC unit 12 and provides structural support andprotection to the internal components from environmental and othercontaminants. In some embodiments, the cabinet 24 may be constructed ofgalvanized steel and insulated with aluminum foil faced insulation.Rails 26 may be joined to the bottom perimeter of the cabinet 24 andprovide a foundation for the HVAC unit 12. In certain embodiments, therails 26 may provide access for a forklift and/or overhead rigging tofacilitate installation and/or removal of the HVAC unit 12. In someembodiments, the rails 26 may fit into “curbs” on the roof to enable theHVAC unit 12 to provide air to the ductwork 14 from the bottom of theHVAC unit 12 while blocking elements such as rain from leaking into thebuilding 10.

The HVAC unit 12 includes heat exchangers 28 and 30 in fluidcommunication with one or more refrigeration circuits. Tubes within theheat exchangers 28 and 30 may circulate refrigerant, such as R-410A,through the heat exchangers 28 and 30. The tubes may be of varioustypes, such as multichannel tubes, conventional copper or aluminumtubing, and so forth. Together, the heat exchangers 28 and 30 mayimplement a thermal cycle in which the refrigerant undergoes phasechanges and/or temperature changes as it flows through the heatexchangers 28 and 30 to produce heated and/or cooled air. For example,the heat exchanger 28 may function as a condenser where heat is releasedfrom the refrigerant to ambient air, and the heat exchanger 30 mayfunction as an evaporator where the refrigerant absorbs heat to cool anair stream. In other embodiments, the HVAC unit 12 may operate in a heatpump mode where the roles of the heat exchangers 28 and 30 may bereversed. That is, the heat exchanger 28 may function as an evaporatorand the heat exchanger 30 may function as a condenser. In furtherembodiments, the HVAC unit 12 may include a furnace for heating the airstream that is supplied to the building 10. While the illustratedembodiment of FIG. 2 shows the HVAC unit 12 having two of the heatexchangers 28 and 30, in other embodiments, the HVAC unit 12 may includeone heat exchanger or more than two heat exchangers.

The heat exchanger 30 is located within a compartment 31 that separatesthe heat exchanger 30 from the heat exchanger 28. Fans 32 draw air fromthe environment through the heat exchanger 28. Air may be heated and/orcooled as the air flows through the heat exchanger 28 before beingreleased back to the environment surrounding the HVAC unit 12. A blowerassembly 34, powered by a motor 36, draws air through the heat exchanger30 to heat or cool the air. The heated or cooled air may be directed tothe building 10 by the ductwork 14, which may be connected to the HVACunit 12. Before flowing through the heat exchanger 30, the conditionedair flows through one or more filters 38 that may remove particulatesand contaminants from the air. In certain embodiments, the filters 38may be disposed on the air intake side of the heat exchanger 30 toprevent contaminants from contacting the heat exchanger 30.

The HVAC unit 12 also may include other equipment for implementing thethermal cycle. Compressors 42 increase the pressure and temperature ofthe refrigerant before the refrigerant enters the heat exchanger 28. Thecompressors 42 may be any suitable type of compressors, such as scrollcompressors, rotary compressors, screw compressors, or reciprocatingcompressors. In some embodiments, the compressors 42 may include a pairof hermetic direct drive compressors arranged in a dual stageconfiguration 44. However, in other embodiments, any number of thecompressors 42 may be provided to achieve various stages of heatingand/or cooling. As may be appreciated, additional equipment and devicesmay be included in the HVAC unit 12, such as a solid-core filter drier,a drain pan, a disconnect switch, an economizer, pressure switches,phase monitors, and humidity sensors, among other things.

The HVAC unit 12 may receive power through a terminal block 46. Forexample, a high voltage power source may be connected to the terminalblock 46 to power the equipment. The operation of the HVAC unit 12 maybe governed or regulated by a control board or controller 48. Thecontrol board 48 may include control circuitry connected to athermostat, sensors, and alarms. One or more of these components may bereferred to herein separately or collectively as the control device 16.The control circuitry may be configured to control operation of theequipment, provide alarms, and monitor safety switches. Wiring 49 mayconnect the control board 48 and the terminal block 46 to the equipmentof the HVAC unit 12.

FIG. 3 illustrates a residential heating and cooling system 50, also inaccordance with present techniques. The residential heating and coolingsystem 50 may provide heated and cooled air to a residential structure,as well as provide outside air for ventilation and provide improvedindoor air quality (IAQ) through devices such as ultraviolet lights andair filters. In the illustrated embodiment, the residential heating andcooling system 50 is a split HVAC system. In general, a residence 52conditioned by a split HVAC system may include refrigerant conduits 54that operatively couple the indoor unit 56 to the outdoor unit 58. Theindoor unit 56 may be positioned in a utility room, an attic, abasement, and so forth. The outdoor unit 58 is typically situatedadjacent to a side of residence 52 and is covered by a shroud to protectthe system components and to prevent leaves and other debris orcontaminants from entering the unit. The refrigerant conduits 54transfer refrigerant between the indoor unit 56 and the outdoor unit 58,typically transferring primarily liquid refrigerant in one direction andprimarily vaporized refrigerant in an opposite direction.

When the system shown in FIG. 3 is operating as an air conditioner, aheat exchanger 60 in the outdoor unit 58 serves as a condenser forre-condensing vaporized refrigerant flowing from the indoor unit 56 tothe outdoor unit 58 via one of the refrigerant conduits 54. In theseapplications, a heat exchanger 62 of the indoor unit 56 functions as anevaporator. Specifically, the heat exchanger 62 receives liquidrefrigerant, which may be expanded by an expansion device, andevaporates the refrigerant before returning it to the outdoor unit 58.

The outdoor unit 58 draws environmental air through the heat exchanger60 using a fan 64 and expels the air above the outdoor unit 58. Whenoperating as an air conditioner, the air is heated by the heat exchanger60 within the outdoor unit 58 and exits the unit at a temperature higherthan it entered. The indoor unit 56 includes a blower or fan 66 thatdirects air through or across the indoor heat exchanger 62, where theair is cooled when the system is operating in air conditioning mode.Thereafter, the air is passed through ductwork 68 that directs the airto the residence 52. The overall system operates to maintain a desiredtemperature as set by a system controller. When the temperature sensedinside the residence 52 is higher than the set point on the thermostat,or a set point plus a small amount, the residential heating and coolingsystem 50 may become operative to refrigerate additional air forcirculation through the residence 52. When the temperature reaches theset point, or a set point minus a small amount, the residential heatingand cooling system 50 may stop the refrigeration cycle temporarily.

The residential heating and cooling system 50 may also operate as a heatpump. When operating as a heat pump, the roles of heat exchangers 60 and62 are reversed. That is, the heat exchanger 60 of the outdoor unit 58will serve as an evaporator to evaporate refrigerant and thereby coolair entering the outdoor unit 58 as the air passes over the heatexchanger 60. The indoor heat exchanger 62 will receive a stream of airblown over it and will heat the air by condensing the refrigerant.

In some embodiments, the indoor unit 56 may include a furnace system 70.For example, the indoor unit 56 may include the furnace system 70 whenthe residential heating and cooling system 50 is not configured tooperate as a heat pump. The furnace system 70 may include a burnerassembly and heat exchanger, among other components, inside the indoorunit 56. Fuel is provided to the burner assembly of the furnace system70 where it is mixed with air and combusted to form combustion products.The combustion products may pass through tubes or piping in a heatexchanger, separate from heat exchanger 62, such that air directed bythe blower 66 passes over the tubes or pipes and extracts heat from thecombustion products. The heated air may then be routed from the furnacesystem 70 to the ductwork 68 for heating the residence 52.

FIG. 4 is an embodiment of a vapor compression system 72 that may beused in any of the systems described above. The vapor compression system72 may circulate a refrigerant through a circuit starting with acompressor 74. The circuit may also include a condenser 76, an expansionvalve(s) or device(s) 78, and an evaporator 80. The vapor compressionsystem 72 may further include a control panel 82 that has an analog todigital (A/D) converter 84, a microprocessor 86, a non-volatile memory88, and/or an interface board 90. The control panel 82 and itscomponents may function to regulate operation of the vapor compressionsystem 72 based on feedback from an operator, from sensors of the vaporcompression system 72 that detect operating conditions, and so forth.

In some embodiments, the vapor compression system 72 may use one or moreof a variable speed drive (VSDs) 92, a motor 94, the compressor 74, thecondenser 76, the expansion valve or device 78, and/or the evaporator80. The motor 94 may drive the compressor 74 and may be powered by thevariable speed drive (VSD) 92. The VSD 92 receives alternating current(AC) power having a particular fixed line voltage and fixed linefrequency from an AC power source, and provides power having a variablevoltage and frequency to the motor 94. In other embodiments, the motor94 may be powered directly from an AC or direct current (DC) powersource. The motor 94 may include any type of electric motor that may bepowered by a VSD or directly from an AC or DC power source, such as aswitched reluctance motor, an induction motor, an electronicallycommutated permanent magnet motor, or another suitable motor.

The compressor 74 compresses a refrigerant vapor and delivers the vaporto the condenser 76 through a discharge passage. In some embodiments,the compressor 74 may be a centrifugal compressor. The refrigerant vapordelivered by the compressor 74 to the condenser 76 may transfer heat toa fluid passing across the condenser 76, such as ambient orenvironmental air 96. The refrigerant vapor may condense to arefrigerant liquid in the condenser 76 as a result of thermal heattransfer with the environmental air 96. The liquid refrigerant from thecondenser 76 may flow through the expansion device 78 to the evaporator80.

The liquid refrigerant delivered to the evaporator 80 may absorb heatfrom another air stream, such as a supply air stream 98 provided to thebuilding 10 or the residence 52. For example, the supply air stream 98may include ambient or environmental air, return air from a building, ora combination of the two. The liquid refrigerant in the evaporator 80may undergo a phase change from the liquid refrigerant to a refrigerantvapor. In this manner, the evaporator 80 may reduce the temperature ofthe supply air stream 98 via thermal heat transfer with the refrigerant.Thereafter, the vapor refrigerant exits the evaporator 80 and returns tothe compressor 74 by a suction line to complete the cycle.

In some embodiments, the vapor compression system 72 may further includea reheat coil in addition to the evaporator 80. For example, the reheatcoil may be positioned downstream of the evaporator relative to thesupply air stream 98 and may reheat the supply air stream 98 when thesupply air stream 98 is overcooled to remove humidity from the supplyair stream 98 before the supply air stream 98 is directed to thebuilding 10 or the residence 52.

It should be appreciated that any of the features described herein maybe incorporated with the HVAC unit 12, the residential heating andcooling system 50, or other HVAC systems. Additionally, while thefeatures disclosed herein are described in the context of embodimentsthat directly heat and cool a supply air stream provided to a buildingor other load, embodiments of the present disclosure may be applicableto other HVAC systems as well. For example, the features describedherein may be applied to mechanical cooling systems, free coolingsystems, chiller systems, or other heat pump or refrigerationapplications.

The description above with reference to FIGS. 1-4 is intended to beillustrative of the context of the present disclosure. The techniques ofthe present disclosure may be incorporated with any or all of thefeatures described above, as well as other systems not described above.In particular, as will be discussed in more detail below, the presentdisclosure provides techniques for controlling operation of an HVACsystem based on a detected presence of refrigerant external a heatexchanger and/or a circuit of the HVAC system. For example, a controlboard of the HVAC system may suspend general or normal operation of theHVAC system and may control operation of a blower configured to inducean air flow across the heat exchanger in response to the detection ofrefrigerant external to the heat exchanger.

To help illustrate, FIG. 5 is a schematic of an HVAC system 100 havingan HVAC unit 102 and a control system 104 (e.g., a controller)configured to control operation of the HVAC unit 102 and/or the HVACsystem 100 generally. The illustrated HVAC system 100 may includeembodiments or components of the HVAC unit 12 shown in FIG. 1,embodiments or components of the residential heating and cooling system50 shown in FIG. 3, a rooftop unit (RTU), or any other suitable HVACsystem. The HVAC unit 102, or portion(s) thereof, may be positionedindoors and/or outdoors, such that the HVAC unit 102 may be an indoorunit and/or an outdoor unit. As described in greater detail below, athermostat 106 of the control system 104 may control general and/ornormal operation of the HVAC unit 102, such as based on a selectedoperating mode or a parameter set point. To this end, the thermostat 106may be configured to provide control signals to the HVAC unit 102 inorder to operate in one or more normal operating modes (e.g., a heatingmode, a cooling mode).

In accordance with present techniques, the HVAC system 100 includes arefrigerant detection and control system 105 configured to detect apresence of refrigerant external to components of the HVAC unit 102configured to circulate refrigerant. To this end, the control system 104includes a control board 108 that may enable or suspend generaloperation of the HVAC unit 102 based on refrigerant detection. Forexample, in response to refrigerant detection, the control board 108 maysuspend supply of power to the thermostat 106, thereby suspending normaloperation of the HVAC unit 102. While operation of the HVAC unit 102 viathe thermostat 106 is suspended, the control board 108 may enable analternate operating mode of the HVAC unit 102. In the alternateoperating mode, a blower 110 of the HVAC unit 102 may induce an air flowacross a heat exchanger and/or other portions of the HVAC unit 102proximate to which refrigerant is detected. In this manner, operation ofthe blower 110 enables dispersing of refrigerant that is detectedexternal to the heat exchanger. Thus, the control board 108 enables theHVAC system 100 to switch between a general operating mode and analternate operating mode based on the detection of refrigerant externalto the heat exchanger.

While the control board 108 is illustrated as being electrically coupledto the HVAC unit 102 via the thermostat 106, in some embodiments, thecontrol board 108 may be electrically coupled to one or more componentsof the HVAC unit 102. In such embodiments, in response to determiningthat refrigerant is present external to the heat exchanger, the controlboard 108 may remove power from the one or more other components (e.g.,one or more components other than the thermostat) that enable generaloperation of the HVAC unit 102 or may otherwise disable operation ofsuch components. For example, the control board 108 may remove powerfrom another control system (e.g., a control system different from thethermostat) configured to enable and control general operation of theHVAC unit 102. Additionally or alternatively, the control board 108 mayremove power from one or more other components of the HVAC unit 102,such as a compressor, a heat exchanger, an expansion valve, and/or othersuitable components. In such embodiments, the thermostat 106 may bebattery-powered, but operation and control of the one or more othercomponents of the HVAC unit 102, via the thermostat 106, may besuspended (e.g., disabled) based on the control board 108 removing powerfrom the one or more other components of the HVAC unit 102.

As illustrated, the HVAC unit 102 includes the compressor 74, thecondenser 76, and the evaporator 80. The HVAC unit 102 is configured tocirculate refrigerant along a circuit 120 including the compressor 74,the condenser 76, and the evaporator 80, as indicated by arrows 122. Asgenerally described above, refrigerant within the circuit 120 mayexchange heat with a working fluid (e.g., air, water) at the evaporator80, for example, by evaporating and heating the refrigerant and coolingthe working fluid. In certain embodiments, the HVAC unit 102 may includeadditional or other components disposed along the circuit 120, such ascomponents described in reference to FIGS. 1-4. Additionally, the HVACunit 102 includes the blower 110 and a sensor 130. The blower 110 isconfigured to direct an air flow across and/or through the evaporator80, as indicated by arrow 132. In certain embodiments, the blower 110may be the blower 66 that directs air across the evaporator 80 and intoductwork for delivery to a conditioned environment. In some embodiments,the blower 110 may direct air across the evaporator 80 and into an areaof the HVAC system 100 separate from a conditioned environment, such asanother compartment/cabinet of the HVAC system 100, an outdoor area, oranother suitable area. The control system 104 and/or the refrigerantdetection and control system 105 may include the sensor 130.Additionally, the control system 104 may include the refrigerantdetection and control system 105, or the refrigerant detection andcontrol system 105 may include the control system 104.

In some instances, refrigerant may escape from the circuit 120, such asfrom tubing (e.g., a coil) within or adjacent to the evaporator 80. Thesensor 130 may detect a presence of refrigerant (e.g., R-1234yf,R-1234ze, R-32, R-454A, R-454C, R-455A, R-447A, R-452B, R-454B, etc.)external to the evaporator 80 and may provide feedback (e.g., an input)to the control system 104 indicative of the presence of refrigerantexternal to the evaporator 80. More specifically, the sensor 130 mayprovide the feedback to the control board 108 of the control system 104.As illustrated, the sensor 130 is positioned at an outlet 134 of theevaporator 80. However, in certain embodiments, the sensor 130 may bepositioned at an inlet 136 of the evaporator 80 and/or at otherlocations adjacent to the evaporator 80 (e.g., proximate, above, orbelow tubing of the evaporator 80). In some embodiments, refrigerantexternal to the evaporator 80 may settle generally below the evaporator80 (e.g., relative to gravity), and the sensor 130 may therefore bepositioned below the evaporator 80 in order to detect the presence ofrefrigerant external to and generally below the evaporator 80.

The control system 104 may receive feedback from the sensor 130 and maycontrol the HVAC unit 102 based on the feedback. For example, thecontrol system 104, via the control board 108, may enable generaloperation of the HVAC unit 102 by supplying power to the thermostat 106in the absence of feedback received from the sensor 130 indicating thatrefrigerant is external to the evaporator 80. Thus, the thermostat 106may control the HVAC unit 102 to operate in a heating operating mode, ina cooling operating mode, based on a temperature set point, based on ahumidity set point, and/or based on other operating modes, set points,and other parameters when the control system 104 (e.g., the controlboard 108) does not receive feedback indicating that refrigerant isdetected external to the evaporator 80. In certain embodiments, such asembodiments of the HVAC system 100 including a battery-poweredthermostat 106, the control system 104, via the control board 108, mayenable general operation of the HVAC unit 102 by supplying power to oneor more components of the HVAC unit 102 in the absence of feedbackreceived from the sensor 130 indicating that refrigerant is external tothe evaporator 80.

Additionally, the control system 104, via the control board 108, maysuspend general operation of the HVAC unit 102 (e.g., suspend control ofthe HVAC unit 102 via the thermostat 106) in response to receivingfeedback from the sensor 130 indicating that refrigerant is detectedexternal to the evaporator 80. Specifically, based on feedback from thesensor 130 indicative of detected refrigerant, the control board 108 maysuspend supply of power to the thermostat 106, thereby suspendingcontrol of the HVAC unit 102 via the thermostat 106. In certainembodiments, such as embodiments of the HVAC system 100 including abattery-powered thermostat 106, the control system 104, via the controlboard 108, may suspend supply of power to one or more components of theHVAC unit 102 in response to receiving feedback from the sensor 130indicating that refrigerant is detected external to the evaporator 80,thereby suspending general operation of the HVAC unit 102. Further, thecontrol system 104, via the control board 108, may cause the blower 110to generate and direct the air flow 132 across the evaporator 80 inresponse to receiving feedback from the sensor 130 indicating thatrefrigerant is detected external to the evaporator 80. In particular,the control board 108 may enable supply of power to the blower 110 basedon the feedback indicative of detected refrigerant.

In certain embodiments of the alternate operating mode, the controlsystem 104, via the control board 108, may operate the blower 110 for apredetermined time period prior to resuming general operation of theHVAC unit 102 via the thermostat 106. That is, upon expiration of thepredetermined period of time, the control board 108 may resume supply ofpower to the thermostat 106. The predetermined time period may be 10seconds, 20 seconds, 30 seconds, 1 minute, 2 minutes, 3 minutes, 4minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10minutes, 15 minutes, 20 minutes, 1 hour, or other suitable time periods.In some embodiments, after operating the blower 110 in accordance withthe alternate operating mode, such as for the predetermined time period,the control system 104 may block operation of the blower 110, the HVACunit 102, and/or the HVAC system 100 for another predetermined timeperiod (e.g., 10 seconds, 20 seconds, 30 seconds, 1 minute, 2 minutes, 3minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9minutes, 10 minutes, 15 minutes, 20 minutes, 1 hour). In certainembodiments, the control system 104 may operate the blower 110 togenerate a particular flow rate of air flow across the evaporator 80, asindicated by arrow 132. For example, the particular flow rate may be 10cubic feet per minute (CFM) per ton of HVAC system 100 cooling capacity,50 CFM per ton of cooling capacity, 100 CFM per ton of cooling capacity,200 CFM per ton of cooling capacity, 300 CFM per ton of coolingcapacity, 400 CFM per ton of cooling capacity, 500 CFM per ton ofcooling capacity, 600 CFM per ton of cooling capacity, 800 CFM per tonof cooling capacity, 1000 CFM per ton of cooling capacity, 2000 CFM perton of cooling capacity, or other suitable flowrates. The control system104 may determine the time period for operating the blower 110, the timeperiod during which operation of the blower 110, the HVAC unit 102,and/or the HVAC system 100 is blocked, and/or the flow rate provided bythe blower 110 based on a type of refrigerant utilized within the HVACsystem 100 (and therefore detected by the sensor 130), a configurationand/or a size of the evaporator 80, and/or any other suitable factors.As used herein, the configuration of the evaporator 80 and/or anotherheat exchanger may include a number of heat exchanger slabs, anorientation of heat exchanger slabs, a configuration of heat exchangertubes (e.g, microchannel), a configuration of fins, and other aspects ofa heat exchanger configuration.

In some embodiments, the feedback from the sensor 130 may indicate anamount of refrigerant (e.g., a volume) and/or a concentration (e.g.,parts per million) of refrigerant relative to other fluid(s) (e.g., air,water). The control system 104, via the control board 108, may controloperation of the HVAC unit 102 (e.g., in the alternate operating mode)based on the amount and/or the concentration of refrigerant. Forexample, in response to the amount and/or concentration of refrigerantexceeding a threshold value, the control system 104, via the controlboard 108, may suspend general operation of the HVAC unit 102 and mayoperate the blower 110 according to the alternate operating mode. Inresponse to the amount and/or concentration of detected refrigerant notexceeding the threshold value and/or falling below the threshold value,the control system 104, via the control board 108, may resume and enablegeneral operation of the HVAC unit 102 via the thermostat 106. Thethreshold value of the concentration of refrigerant in air may be 0.010pounds of refrigerant per cubic foot of air (pounds per cubic foot),0.015 pounds per cubic foot, 0.020 pounds per cubic foot, 0.025 poundsper cubic foot, 0.030 pounds per cubic foot, 0.040 pounds per cubicfoot, or any other suitable concentrations. In certain embodiments, thecontrol system 104 may determine the concentration of refrigerant in airbased on the feedback indicative of the amount of refrigerant externalto the evaporator 80 and/or other component of the HVAC unit 102. Thecontrol system 104 may determine the threshold value based on a type ofrefrigerant, a configuration and/or a size of the evaporator 80, and/orany other suitable factors.

The control system 104 may include processor circuity 140 and a memory142. The processor circuity 140 may be configured to execute software,such as software stored in the memory 142, configured to receiveinformation from components of the HVAC system 100, send informationand/or commands to components of the HVAC system 100, and/or otherwiseadjust and/or control the HVAC system 100. Moreover, the processorcircuity 140 may include multiple microprocessors, one or more“general-purpose” microprocessors, one or more special-purposemicroprocessors, and/or one or more application specific integratedcircuits (ASICS), or some combination thereof. For example, theprocessor circuity 140 may include one or more reduced instruction set(RISC) or complex instruction set (CISC) processors. The memory 142 mayinclude a volatile memory, such as random access memory (RAM), and/or anonvolatile memory, such as read-only memory (ROM). The memory 142 maystore a variety of information and may be used for various purposes.That is, the memory 142 may store data, executable instructions, and/orany other suitable data. For example, the memory 142 may storeprocessor-executable instructions, such as firmware or software forcontrolling the HVAC system 100, for the processor circuity 140 toexecute. The memory 142 may include ROM, flash memory, a hard drive, orany other suitable optical, magnetic, or solid-state storage medium, ora combination thereof.

The processor circuity 140 and/or the memory 142 may be located in anysuitable portion of the HVAC system 100. The memory 142 may be anysuitable article of manufacture that can serve as a medium to storeprocessor-executable code, data, or the like. These articles ofmanufacture may represent computer-readable medium or any suitable formof memory or storage that may store the processor-executable code usedby the processor circuity 140 to perform the presently disclosedtechniques. The memory 142 may represent a non-transitorycomputer-readable storage medium or any suitable form of memory orstorage that may store the processor-executable code for execution bythe processor circuity 140. It should be noted that “non-transitory”merely indicates that the medium is tangible and not a signal. Incertain embodiments, the memory 142 may be a cloud-based memory and/orthe control system 104 may access the cloud-based memory.

FIG. 6 is a schematic of an embodiment of the HVAC system 100 includingthe HVAC unit 102, the thermostat 106, and the control board 108. Asillustrated, the control board 108 includes a microprocessor 200, athermostat relay 210 in a closed position, and a blower relay 220 in anopen position. Additionally, FIG. 7 is a schematic of an embodiment ofthe control board 108 illustrating the thermostat relay 210 is in anopen position and the blower relay 220 in a closed position. Themicroprocessor 200 may switch the thermostat relay 210 and the blowerrelay 220 between the open and closed positions based on feedback fromthe sensor 130. For example, based on feedback from the sensor 130indicating that refrigerant is not detected external to the evaporator80 (e.g., any detected refrigerant is below a threshold value) and/or inthe absence of feedback from the sensor 130 indicating that refrigerantis detected external to the evaporator 80, the microprocessor 200 maycontrol the thermostat relay 210 to be in the closed position and theblower relay 220 to be in the open position, as illustrated in FIG. 6.Based on feedback from the sensor 130 indicating that refrigerant isdetected external to the evaporator 80, the microprocessor 200 mayswitch the thermostat relay 210 to the open position and switch theblower relay 220 to the closed position, as illustrated in FIG. 7.

In the closed position, the thermostat relay 210 enables operation ofthe HVAC unit 102 via the thermostat 106. For example, in the closedposition, the thermostat relay 210 enables supply of power to thethermostat 106. More specifically, the closed thermostat relay 210enables supply of power from HVAC unit 102 to the thermoset 106 via thecontrol board 108 and the thermostat relay 210. As such, the thermostatrelay 210 may be in the closed position during general operation of theHVAC unit 102. In the open position, the thermostat relay 210 maysuspend operation of the HVAC unit 102 via the thermostat 106 byinterrupting supply of power to the thermostat 106. In this way,operation of components of the HVAC unit 102, such as the compressor 74,are suspended, which may reduce or prevent refrigerant from escaping theevaporator 80. In certain embodiments, in the closed position, thethermostat relay 210 may enable supply of power to one or morecomponents of the HVAC unit 102, such as embodiments including abattery-powered thermostat 106. In such embodiments, in the openposition, the thermostat relay 210 may suspend operation of the HVACunit 102 by interrupting supply of power to the one or more componentsof the HVAC unit 102.

In the open position, the blower relay 220 may suspend operation of theblower 110 via the control board 108. For example, when the blower relay220 is open, the control board 108 does not supply power to the blower110. However, in certain embodiments, the HVAC system 100 may still beconfigured to operate the blower 110 in another manner while the blowerrelay 220 is in the open position of FIG. 6, such as during an operatingmode (e.g., normal operating mode) that includes operation of the blower110. In the closed position, the blower relay 220 may enable operationof the blower 110, thereby enabling the blower 110 to generate anddirect air flow over or through the evaporator 80 to disperserefrigerant present external to the evaporator 80. For example, theblower relay 220 may complete (e.g., close) an electrical circuitconnected to the HVAC unit 102, the control board 108, and the blower110 while in the closed position. In this way, power is supplied fromthe HVAC unit 102 to the blower 110 via the control board 108 and theclosed blower relay 220. The thermostat relay 210 and the blower relay220 may be an electrical relay, a mechanical relay, anelectro-mechanical relay, a magnetic relay, and/or any other suitablerelay.

The microprocessor 200 may control (e.g., switch) the thermostat relay210 and the blower relay 220 between the open and closed positions basedon a voltage signal received from the sensor 130. The voltage signal mayindicate the presence or absence of refrigerant external to theevaporator 80. For example, based on the voltage exceeding a thresholdvalue, the microprocessor 200 may switch the thermostat relay 210 fromthe closed position of FIG. 6 to the open position of FIG. 7 and mayswitch the blower relay 220 from the open position of FIG. 6 to theclosed position of FIG. 7. The threshold value may be 1 VDC, 2 VDC, 3VDC, 3.5 VDC, 4 VDC, 5 VDC, or other suitable voltages. In someembodiments, based on the voltage being outside a threshold range, themicroprocessor 200 may switch the thermostat relay 210 from the closedposition of FIG. 6 to the open position of FIG. 7 and may switch theblower relay 220 from the open position of FIG. 6 to the closed positionof FIG. 7. A lower limit of the threshold range may be 0.1 VDC, 0.2 VDC,0.5 VDC, 1 VDC, 2 VDC, or other suitable voltages. An upper limit of thethreshold range may be 2 VDC, 3 VDC, 4 VDC, 4.5 VDC, 5 VDC, 6 VDC, andother suitable voltages. In certain embodiments, components of the HVACsystem 100, such as the sensor 130, the control board 108, portion(s) ofthe control board 108 (e.g., the microprocessor 200, the thermostatrelay 210, the blower relay 220), the thermostat 106, portion(s) of thethermostat 106, the HVAC unit 102, portion(s) of the HVAC unit 102, maycommunicate with one another via Universal AsynchronousReceiver/Transmitter (UART) communication and/or via serialcommunication (e.g., RS-485/232).

After operating the blower 110 for a specific time period (e.g., in thealternate operating mode with the thermostat relay 210 in the openposition and the blower relay 220 in the closed position of FIG. 7), themicroprocessor 200 may switch the thermostat relay 210 back to theclosed position and the blower relay 220 to the open position, asillustrated in FIG. 6. As described above, the specific time period foroperating the blower 110 may be any suitable time period, such as 5minutes.

Accordingly, the present disclosure provides systems and methodsconfigured to detect refrigerant external to a circuit of an HVACsystem, such as refrigerant that is external to a heat exchanger of theHVAC system, and configured to control the HVAC system based on thedetection. For example, in response to determining that refrigerant(e.g., a threshold amount or concentration of refrigerant) is presentexternal to the heat exchanger, a control board of the HVAC system maysuspend supply of power to a thermostat of the HVAC system that operatesto enable and control general (e.g., normal) operation of the HVACsystem. Additionally, in response to determining that refrigerant isdetected external to the heat exchanger, the control board may supplypower to a blower of the HVAC system that induces an air flow through oralong the HVAC system, such as across the heat exchanger, therebydispersing refrigerant that is located external to the heat exchanger.Controlling operation of the HVAC system based on the determination thatrefrigerant is present external to the heat exchanger enables the HVACsystem to reduce or prevent additional refrigerant from escaping theheat exchanger or other portion of the refrigerant circuit, reduce anamount and/or a concentration of the refrigerant mixed with air adjacentto and/or flowing across the heat exchanger, and/or comply with certainindustry standards. As such, the systems and methods described hereinimprove/facilitate operation, maintenance, and management of the HVACsystem.

The techniques presented and claimed herein are referenced and appliedto material objects and concrete examples of a practical nature thatdemonstrably improve the present technical field and, as such, are notabstract, intangible or purely theoretical. Further, if any claimsappended to the end of this specification contain one or more elementsdesignated as “means for [perform]ing [a function] . . . ” or “step for[perform]ing [a function] . . . ”, it is intended that such elements areto be interpreted under 35 U.S.C. 112(f). However, for any claimscontaining elements designated in any other manner, it is intended thatsuch elements are not to be interpreted under 35 U.S.C. 112(f).

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

What is claimed is:
 1. A heating, ventilation, and/or air conditioning(HVAC) system, comprising: a heat exchanger configured to exchange heatbetween a refrigerant and an air flow; a blower configured to induce theair flow across the heat exchanger; and a control board configured to:receive an input indicative of a presence of refrigerant external to theheat exchanger; and adjust operation of the blower based on the input.2. The HVAC system of claim 1, comprising a sensor configured to providethe input indicative of the presence of refrigerant external to the heatexchanger to the control board, wherein the sensor is disposed proximateto the heat exchanger.
 3. The HVAC system of claim 1, wherein the heatexchanger comprises an evaporator configured to exchange heat betweenthe air flow and the refrigerant.
 4. The HVAC system of claim 1,comprising a thermostat configured to control a normal operating mode ofthe HVAC system, wherein the control board is configured to supply powerto the thermostat in the normal operating mode.
 5. The HVAC system ofclaim 4, wherein the control board is configured to suspend the normaloperating mode of the HVAC system by suspending supply of power to thethermostat based on the input and configured to operate the blower basedon the input.
 6. The HVAC system of claim 1, wherein the control boardcomprises: a thermostat relay configured to supply power to a thermostatof the HVAC system in a closed position of the thermostat relay andsuspend supply of power to the thermostat in an open position of thethermostat relay; and a blower relay configured to supply power to theblower in a closed position of the blower relay and suspend supply ofpower to the blower in an open position of the blower relay.
 7. The HVACsystem of claim 6, wherein the control board is configured to adjust thethermostat relay to the open position and to adjust the blower relay tothe closed position based on the input.
 8. The HVAC system of claim 1,wherein the input comprises a voltage, and wherein the control board isconfigured to suspend supply of power to a thermostat of the HVAC systemand initiate supply of power to the blower based on the voltageexceeding a threshold value.
 9. The HVAC system of claim 1, comprisingan HVAC unit comprising the heat exchanger, a compressor, and one ormore expansion valves, wherein the HVAC unit is configured to operate ina normal operating mode, and wherein the control board is configured tosupply power to the compressor, the one or more expansion valves, orboth, in the normal operating mode.
 10. The HVAC system of claim 9,wherein the control board is configured to suspend the normal operatingmode of the HVAC system by suspending supply of power to the compressor,the one or more expansion valves, or both, based on the input andconfigured to operate the blower based on the input.
 11. Anon-transitory computer-readable storage medium for a heating,ventilation, and/or air conditioning (HVAC) system comprisinginstructions that, when executed by a processor, cause the processor to:receive an input indicative of a presence of refrigerant external to aheat exchanger of the HVAC system; and adjust operation of a blower ofthe HVAC system based on the input.
 12. The non-transitorycomputer-readable storage medium of claim 11, wherein the inputindicative of the presence of refrigerant is indicative of an amount ofrefrigerant, and wherein the instructions, when executed by theprocessor, cause the processor to: determine a concentration ofrefrigerant in air based on the amount of refrigerant; and adjust theoperation of the blower in response to the concentration of refrigerantin air exceeding a threshold value.
 13. The non-transitorycomputer-readable storage medium of claim 12, wherein the instructions,when executed by the processor, cause the processor to determine thethreshold value based on a type of the refrigerant, a configuration ofthe heat exchanger, a size of the heat exchanger, or a combinationthereof.
 14. The non-transitory computer-readable storage medium ofclaim 11, wherein the instructions, when executed by the processor,cause the processor to: suspend a normal operating mode of the HVACsystem by suspending supply of power to a thermostat of the HVAC systembased on the input; and operate the blower based on the input.
 15. Thenon-transitory computer-readable storage medium of claim 11, wherein theinstructions, when executed by the processor, cause the processor tosuspend a normal operating mode of the HVAC system by suspending supplyof power to a compressor of the HVAC system, one or more expansionvalves of the HVAC system, or both, based on the input.
 16. Thenon-transitory computer-readable storage medium of claim 11, wherein theinstructions, when executed by the processor, cause the processor tooperate the HVAC system in a normal operating mode based on an absenceof the input.
 17. A heating, ventilation, and/or air conditioning (HVAC)system, comprising: a heat exchanger configured to exchange heat betweena refrigerant and an air flow; a blower configured to induce the airflow across the heat exchanger; and a control board comprising: athermostat relay configured to selectively supply and suspend power to athermostat of the HVAC system; a blower relay configured to selectivelysupply and suspend power to the blower; and a processor configured tocontrol the thermostat relay and the blower relay, wherein the processoris configured to: receive an input indicative of a presence of therefrigerant external to the heat exchanger; and adjust operation of theblower via control of the blower relay based on the input.
 18. The HVACsystem of claim 17, wherein the processor is configured to adjust thethermostat relay to an open position of the thermostat relay to suspendpower to the thermostat and adjust the blower to a closed position ofthe blower relay to supply power to the blower in response to the input.19. The HVAC system of claim 17, comprising the thermostat configured toenable a normal operating mode of the HVAC system, wherein the processoris configured to adjust the thermostat relay to a closed position of thethermostat relay to enable supply of power to the thermostat and enablethe normal operating mode via the thermostat.
 20. The HVAC system ofclaim 17, wherein the heat exchanger comprises an evaporator configuredto exchange heat between the air flow and the refrigerant.